Remove enableReadOnlyMode and disableReadyOnlyMode docs in panes

[nguyen-dows]

This PR remove enableReadOnlyMode and disableReadyOnlyMode docs in panes.md until it goes live in a future release.

Those docs have already been saved in a release branch (release-1.18) so all we need to do is remove them from main.

[learn-build-service-prod[bot]]

Learn Build status updates of commit ba35473:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
TerminalDocs/panes.md	:white_check_mark:Succeeded	View

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